Method of compacting an anodically produced layer of oxide on parts of aluminum or aluminum alloy

Abstract

A method is described of compacting an anodically produced layer of oxide on parts of aluminum or aluminum alloy. In accordance with the invention, the oxide layer is compacted in two process stages, the parts being pretreated in the first process stage in a solution containing about 6% cobalt fluoride and about 30% nickel fluoride in completely desalinified water at about 30° C. for about 10 minutes and then being treated in a second process stage in completely desalinified water with the addition of a coating inhibitor of about 2 ml/l of triazine derivative at an operating temperature of about 70° C. to the boiling point for about 50 minutes.

What is claimed is: 
     
       1. A method of compacting an anodically produced relatively thin layer on parts of aluminum or aluminum-alloy, comprising compacting said oxide layer in two process stages, wherein in said first stage, said parts are treated in a solution of about 6% cobalt fluoride and about 30% nickel fluoride in completely desalinated water at about 30° C. for about 10 minutes and in said second stage said parts are treated in completely desalinated water containing about 2 ml/l of a [1,3,5-]triazine derivative at a temperature of about 70° C. to the boiling point for about 50 minutes. 
     
     
       2. A method according to claim 1 wherein said triazine is a 1,3,5-triazine. 
     
     
       3. A method according to claim 2 wherein said second stage is carried out at a temperature of about 70° C. 
     
     
       4. A method according to claim 3 wherein said 1,3,5-triazine derivative is isocyanuric acid. 
     
     
       5. A method according to claim 2, wherein said anodically produced oxide layer is 10 to 12 μm thick. 
     
     
       6. A method according to claim 2 wherein said second stage is carried out at about 98° C. 
     
     
       7. A method according to claim 6 wherein said 1,3,5-triazine is isocyanuric acid.